This invention is directed to drive systems for moving walkways and, more particularly, to drive systems for accelerating and decelerating moving walkways.
In the past, a wide variety of moving walkways, some with and some without accelerating and decelerating zones have been proposed. One walkway that includes accelerating and decelerating zones is described in U.S. Pat. No. 3,939,959 entitled "Accelerating and Decelerating Moving Walkway" by Phillip Dunstan et al. The accelerating and decelerating moving walkway described in U.S. Pat. No. 3,939,959 includes a plurality of interconnected platforms movable in an oval, substantially planar, horizontal path of travel having lengthy linear sides joined by curved ends. An acceleration zone and a deceleration zone are located at either end. The platforms are interconnected by chains or cables movably attached to cam followers. The cam followers follow acceleration and deceleration cams located beneath the platforms. The cams cause the chains or cables interconnecting the platforms to move in a manner such that platform overlap is controlled. In the accelerating and decelerating zones the platforms overlap by a substantial amount. In these regions people and/or freight board and exit from the walkway. Between the acceleration and deceleration zones are constant speed zones. In the constant speed zones the amount of platform overlap is at a minimum, whereby the relative speed of movement is at a maximum.
Various types of apparatus have been proposed for driving accelerating and decelerating moving walkways. The particular system described in U.S. Pat. No. 3,939,959 comprises a plurality of collars located beneath the platforms and affixed to a driven chain or belt. The collars are adapted to grip drive lugs that project downwardly from support plates mounted beneath the platforms. Since the collars are driven, they move a platform when its lug is gripped by a collar. And, since the platforms are interconnected, the gripped, driven platforms move the nongripped platforms. This mechanism has a number of disadvantages that make it undesirable for widespread use in a various environments. For example, because the interconnection system is mechanical, it is subject to wear and breakdown. As a result constant maintenance is necessary.
In the past, linear induction drive systems have been proposed for use in a number of environments. For example, they have been proposed for use in moving monorail passenger cars. However, monorail passenger car systems differ substantially from moving walkways in that they include separable items, e.g., a single car or several cars that can be independently accelerated or decelerated in accordance with the energy applied to the linear induction drive system at various points. Contrariwise, a moving walkway comprising a series of platforms that encompass an entire path of travel. In this regard, proposals have also been made to use linear induction drive systems in conjunction with moving walkways that do not include acceleration and deceleration zones. Because such walkway systems do not provide the acceleration and deceleration benefits, their usefulness is limited. More importantly, however, because they do not include acceleration and deceleration zones, relatively conventional linear induction drive systems can be used.
One proposal to utilize a linear induction drive system for an accelerating and decelerating moving walkway system that does not include overlapping platforms has been made. That proposal is described in U.S. Pat. No. 3,693,549 entitled "Conveyors" by Gerard Cuenord et al. The moving walkway described in U.S. Pat. No. 3,693,549 is based on sliding of the peripheral edges of the platforms in acceleration and deceleration zones. The linear induction drive system disclosed in this patent will not work satisfactorily with an overlapping type acceleration and deceleration moving walkway using a center platform cam/cable coupling arrangement because the coupling arrangement prevents the inductive interaction with the main body of the platforms, required by this patented system, from occurring.
Furthermore, the reaction rail mechanisms of many prior art devices is often formed in an arm or bracket that projects downwardly at right angles to the path of travel of the platforms being moved. This arrangement is particularly disadvantageous when it is desired to form an accelerating and decelerating moving walkway having a low profile, i.e., a minimum amount of vertical height from the floor or ground on which the moving walkway is mounted.
Therefore, it is an object of this invention to provide a new and improved linear induction drive system.
It is a further object of this invention to provide a new and improved linear induction drive system for a moving walkway that does not increase the vertical profile of the walkway.
It is yet another object of this invention to provide a new and improved linear induction drive system for an accelerating and decelerating moving walkway.
It is a still further object of this invention to provide a new and improved reaction rail suitable for use in a linear induction drive system.